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An optical time-delay estimate for the double gravitational lens system B1600+434

I. Burud·J. Hjorth·A. O. Jaunsen·M. I. Andersen·H. Korhonen·J. W. Clasen·J. Pelt·F. P. Pijpers·P. Magain·R. OEstensen
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Abstract

We present optical I-band light curves of the gravitationally lensed double QSO B1600+434 from observations obtained at the Nordic Optical Telescope (NOT) between April 1998 and November 1999. The photometry has been performed by simultaneous deconvolution of all the data frames, involving a numerical lens galaxy model. Four methods have been applied to determine the time delay between the two QSO components, giving a mean estimate of Δ_t = 51+/-4 days (95% confidence level). This is the fourth optical time delay ever measured. Adopting a Omega=0.3, Lambda=0 Universe and using the mass model of Maller et al. (2000), this time-delay estimate yields a Hubble parameter of H_0=52 (+14, -8) km s^-1 Mpc^-1 (95% confidence level) where the errors include time-delay as well as model uncertainties. There are time-dependent offsets between the two (appropriately shifted) light curves that indicate the presence of external variations due to microlensing.

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I. Burud, J. Hjorth, A. O. Jaunsen, M. I. Andersen, H. Korhonen, J. W. Clasen, J. Pelt, F. P. Pijpers, P. Magain, R. OEstensen. 2000-07-11. An optical time-delay estimate for the double gravitational lens system B1600+434. https://doi.org/10.1086/317213

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